The National Journal rankings are notoriously unreliable. In other years, they had Obama, Kerry and our own Danny Akaka ranked as "the most liberal." It is not just progressives who discount the NJ rankings. Conservatives do as well. From the conservative website, Politico:

"'It's more 'loyalty' rankings than conservative/democratic rankings,' one Republican campaign adviser told me. 'It's as if they haven't updated their system to reflect the way the parties are changing. Voting 100% with Dems makes you the most liberal, voting 100% with the GOP makes you the most conservative.'

'The labels are junk, but it is interesting because it is a rating scale that is grounded in politics not ideology,' Soren Dayton, senior communications strategist at New Media Strategies told me. 'It answers the quesion, 'Who is most likely to vote with the whip?'

In its 2012 rankings, it had Mitch McConnell as more conservative than either Marco Rubio or Rand Paul. In fact, Rand Paul was ranked as the 32nd "most conservative" senator.

In my view, Mazie Hirono is slightly more liberal than Schatz. And Bernie Sanders of Vermont and Elizabeth Warren of Massachusetts, are more liberal than either of them. But since the "metrics" used for ranking elected officials seems to depend upon how often they vote with the leadership, Sanders, Warren and Hirono are more "mavericky" than the freshman senator, Schatz. I had been worried that Schatz, as former chair of the Hawaii for Obama campaign, might be too reluctant to disagree with the President. So far, he has broken with the White House on important issues, like the preparations for war against Syria and Fast Track authorization for the Trans-Pacific Partnership. Independence from the President, when appropriate and independence from Wall Street, are what I care about in a Democratic senator. Not how often he votes with the Senate leadership.